Sounds tough. One thing you could try would be don't reply for a while. Not in the treat em' mean sense, but just to give her time and you both a bit of perspective. If she was the last one to get back to you, just leave it for a bit. You can get back to her in due course and you can focus on you, whilst you decide when is best to reply. Like you said, it can sometimes be unfair to put an emotional burden on another, so it may give her a bit of breathing space and allow her in time to open up on any feelings she may have. If you're always the one to immediately reply to her, then she has the advantage. I'm not saying that she's doing it on purpose, but she may not realise that it is demanding on you. Just play it cool! Good luck!